Flue gas purificn., including desulphurisation - using dry sorbent for one stream and scrubbing liquor for other to give non-corrosive combined stream

摘要

Removal of SO2 and other harmful matter from flue gas is effected by scrubbing with a liquor contg. ca(OH)2 and opt. CaO, sepg. the insol. Ca cpds. and recycling the liquor, after adding Ca(OH)2 and/or CaO if necessary. The improvements are that SO2 and other harmful matter are removed from pt. of the flue gas using powdered CaO and/or Ca(OH)2 as sorbent and both gas purified gas fractions are combined before discharge to the atmos., whilst (pt. of) the sorbent used for dry purificn. is added to the wash liquor used in wet purificn. Pref. the flue gas fractions are purified before entering a chimney. The dry sorbent is circulated and fresh sorbent is added. Spent sorbent is removed and crushed and pref. slaked before adding to the wash liquor circulation. The spent sorbent is introduced into the furnace. The combined gas stream has a dew point above that of corrosive matter still remaining in the flue gas, preventing damage to the discharge channels and chimney and avoiding the need to heat the purified flue gas from the wet purificn. stage.